Switched reluctance motors have been used for years in a number of applications because they are generally more economical to run than other types of motors, such as brushless permanent magnet motors. This is due, in part, to the design of switched reluctance motors which have poles on both the rotor and stator, and phase windings only on the stator. Switched reluctance motors are generally more expensive than other types of less sophisticated motors, however, because they employ electronic circuitry for controlling the current in each of the motor phases. Although, with the cost of electronic circuitry reducing, switch reluctance motors are becoming more cost competitive. In fact, switch reluctance motors have recently been chosen over other types of motors for a number of applications. This is particularly the case in direct drive applications where the need for complicated gear trains is eliminated.
Known switched reluctance motors have several drawbacks and are still in need of improvement. For example, switched reluctance motors can make a siren noise that is caused by the interaction of the rotor and stator pole tips and the cavity spaces between the poles as the rotor turns inside the stator. Also, for single phase switched reluctance motors, unless the rotor and stator poles are properly aligned when the motor comes to rest, consistent motor start-up is not possible. In some positions, the motor will not even start. One solution to this later problem is to install permanent magnets in the stator assembly adjacent to the stator poles. A drawback with this solution, however, is that there is no quick, easy and economical technique for installing the permanent magnets within the coil windings.
The present invention seeks to eliminate or at least minimize some of these drawbacks.